Multilayered filter device

ABSTRACT

A filter device includes a stack including a plurality of dielectric layers stacked together, and first to third resonators integrated with the stack. Each of the first to third resonators includes a first conductor part and a second conductor part electrically connected to the first conductor part and having an impedance smaller than an impedance of the first conductor part. The first conductor part and the second conductor part are arranged at positions different from each other in a stacking direction.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a multilayered filter device includinga resonator constituted of a distributed constant line.

Description of the Related Art

One of electronic components used in a communication apparatus is aband-pass filter including a plurality of resonators. Each of theplurality of resonators is constituted of, for example, a distributedconstant line. The distributed constant line is configured to have apredetermined line length.

US 2013/0307640 A1 discloses a band-pass filter with three stagesconfigured by using three transmission-line resonators. Each of thetransmission-line resonators according to US 2013/0307640 A1 is, inparticular, a stepped-impedance resonator (hereinafter also referred toas an SIR). US 2013/0307640 A1 describes an SIR including a firsttransmission line, a second transmission line connected to one end ofthe first transmission line, and a third transmission line connected tothe other end of the first transmission line.

Miniaturization of band-pass filters used in small-sized communicationapparatuses, in particular, has been desired. However, in a case of aband-pass filter including a resonator formed of a distributed constantline, it is difficult to realize miniaturization of the band-pass filterdue to the distributed constant line constituting the resonator.

US 2013/0307640 A1 describes a technique in which a capacitive elementis loaded onto the first transmission line to miniaturize the SIR.However, in the SIR according to US 2013/0307640 A1, the second andthird transmission lines are connected respectively to both ends of thefirst transmission line. Thus, the technique described in US2013/0307640 A1 has a disadvantage of being difficult to reduce an areafor arranging the SIR.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a multilayered filterdevice that can be miniaturized.

A multilayered filter device according to the present invention includesa stack including a plurality of dielectric layers stacked together, andat least one resonator integrated with the stack. The at least oneresonator includes a first conductor part and a second conductor partelectrically connected to the first conductor part and having animpedance smaller than an impedance of the first conductor part. Thefirst conductor part and the second conductor part are arranged atpositions different from each other in a stacking direction of theplurality of dielectric layers.

In the multilayered filter device according to the present invention,each of the first conductor part and the second conductor part may be adistributed constant line.

The multilayered filter device according to the present invention mayfurther include at least one through hole connecting the first conductorpart and the second conductor part.

The multilayered filter device according to the present invention mayfurther include a plurality of terminals. In this case, the stack mayinclude a first surface and a second surface located at both ends in thestacking direction. The plurality of terminals may be arranged on thefirst surface. The second conductor part may be arranged between thefirst conductor part and the first surface in the stacking direction.

In the multilayered filter device according to the present invention,the first conductor part may include a plurality of portions extendingin a plurality of directions that are orthogonal to the stackingdirection and are different from each other.

In the multilayered filter device according to the present invention,the plane shape of the stack when seen in one direction parallel to thestacking direction may be long in one direction. In this case, the shapeof the second conductor part may be long in a longitudinal direction ofthe plane shape of the stack. Alternatively, the shape of the secondconductor part may be long in a direction crossing the longitudinaldirection of the plane shape of the stack.

In the multilayered filter device according to the present invention,the at least one resonator may include a first resonator, a secondresonator, and a third resonator arranged between the first resonatorand the second resonator in a circuit configuration. In this case, thestack may include a first side surface and a second side surface locatedat both ends in a direction orthogonal to the stacking direction. Thefirst resonator may be arranged at a position closer to the first sidesurface than the second side surface. The second resonator may bearranged at a position closer to the second side surface than the firstside surface.

At least part of the third resonator may be arranged between the firstresonator and the second resonator when seen in one direction parallelto the stacking direction.

The first conductor part of the first resonator and the first conductorpart of the second resonator may be arranged at the same position in thestacking direction. The first conductor part of the third resonator maybe arranged at a position different from a position of the firstconductor part of each of the first resonator and the second resonatorin the stacking direction. In this case, part of the first conductorpart of the first resonator and part of the first conductor part of thesecond resonator may overlap the first conductor part of the thirdresonator when seen in one direction parallel to the stacking direction.

The second conductor part of the first resonator and the secondconductor part of the second resonator may be arranged at the sameposition in the stacking direction. The second conductor part of thethird resonator may be arranged at a position different from a positionof the second conductor part of each of the first resonator and thesecond resonator in the stacking direction. In this case, part of thesecond conductor part of the first resonator and part of the secondconductor part of the second resonator may overlap the second conductorpart of the third resonator when seen in one direction parallel to thestacking direction.

The first conductor part of the third resonator may have an asymmetricalshape.

The shape of the first conductor part of the third resonator may bedifferent from the shape of the first conductor part of the firstresonator and the shape of the first conductor part of the secondresonator. The shape of the second conductor part of the third resonatormay be different from the shape of the second conductor part of thefirst resonator and the shape of the second conductor part of the secondresonator.

The multilayered filter device according to the present invention mayfurther include a first stub resonator electrically connected to thefirst conductor part of the first resonator, and a second stub resonatorelectrically connected to the first conductor part of the secondresonator.

In the multilayered filter device according to the present invention,the first conductor part of the at least one resonator and the secondconductor part of the at least one resonator are arranged at positionsdifferent from each other in the stacking direction of the plurality ofdielectric layers. Thus, according to the present invention, it ispossible to provide a multilayered filter device that can beminiaturized.

Other and further objects, features and advantages of the presentinvention will appear more fully from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram showing a circuit configuration of amultilayered filter device according to a first embodiment of thepresent invention.

FIG. 2 is a perspective view showing an external appearance of themultilayered filter device according to the first embodiment of thepresent invention.

FIGS. 3A to 3C are explanatory diagrams showing respective patternedsurfaces of a first to a third dielectric layer of a stack of themultilayered filter device according to the first embodiment of thepresent invention.

FIGS. 4A to 4C are explanatory diagrams showing respective patternedsurfaces of a fourth to a sixth dielectric layer of the stack of themultilayered filter device according to the first embodiment of thepresent invention.

FIGS. 5A to 5C are explanatory diagrams showing respective patternedsurfaces of a seventh to a ninth dielectric layer of the stack of themultilayered filter device according to the first embodiment of thepresent invention.

FIG. 6 is perspective view showing an inside of the stack of themultilayered filter device according to the first embodiment of thepresent invention.

FIG. 7 is a perspective view showing part of the inside of the stack ofthe multilayered filter device according to the first embodiment of thepresent invention.

FIG. 8 is a perspective view showing part of the inside of the stack ofthe multilayered filter device according to the first embodiment of thepresent invention.

FIG. 9 is a characteristic chart showing pass attenuationcharacteristics of the multilayered filter device according to the firstembodiment of the present invention.

FIG. 10 is a circuit diagram showing a circuit configuration of amultilayered filter device according to a second embodiment of thepresent invention.

FIG. 11 is an explanatory diagram showing a patterned surface of aseventh dielectric layer of a stack of the multilayered filter deviceaccording to the second embodiment of the present invention.

FIG. 12 is a perspective view showing an internal structure of the stackof the multilayered filter device according to the second embodiment ofthe present invention.

FIG. 13 is a circuit diagram showing a circuit configuration of amultilayered filter device according to a third embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

Embodiments of the present invention will now be described in detailwith reference to the drawings. First, reference is made to FIG. 1 todescribe a configuration of a multilayered filter device (hereinafterreferred to simply as a filter device) 1 according to a first embodimentof the present invention. FIG. 1 is a circuit diagram showing a circuitconfiguration of the filter device 1. The filter device 1 is configuredto function as a band-pass filter that selectively allows a signal of afrequency in a predetermined passband to pass.

The filter device 1 according to the present embodiment includes atleast one resonator. In particular, in the present embodiment, thefilter device 1 includes, as the at least one resonator, a firstresonator 10, a second resonator 20, and a third resonator 30 arrangedbetween the first resonator 10 and the second resonator 20 in thecircuit configuration. In the present application, the expression of “inthe (a) circuit configuration” is used not to indicate a layout in thephysical configuration but to indicate a layout in the circuit diagram.

The first to third resonators 10, 20, and 30 are configured so that thefirst resonator 10 and the third resonator 30 are adjacent to each otherin the circuit configuration to be electromagnetically coupled to eachother, and the second resonator 20 and the third resonator 30 areadjacent to each other in the circuit configuration to beelectromagnetically coupled to each other. In FIG. 1 , a curve with asign K13 represents an electric field coupling between the firstresonator 10 and the third resonator 30, and a curve with a sign K23represents an electric field coupling between the second resonator 20and the third resonator 30.

The first resonator 10 is electromagnetically coupled to the secondresonator 20 not adjacent to the first resonator 10 in the circuitconfiguration. Such electromagnetically coupling between two resonatorsnot adjacent to each other in the circuit configuration is referred toas cross coupling. In FIG. 1 , a curve with a sign K12 represents amagnetic field coupling between the first resonator 10 and the secondresonator 20.

The first resonator 10 includes a first conductor part 11 and a secondconductor part 12 having an impedance smaller than that of the firstconductor part 11. The first conductor part 11 and the second conductorpart 12 are electrically connected to each other. The first conductorpart 11 is connected to ground. Each of the first conductor part 11 andthe second conductor part 12 is a distributed constant line. Inparticular, in the present embodiment, the first conductor part 11 is adistributed constant line having a small width, and the second conductorpart 12 is a distributed constant line having a width larger than thatof the first conductor part 11.

The first resonator 10 further includes a third conductor part 13electrically connecting the first conductor part 11 and the secondconductor part 12. The third conductor part 13 may include a distributedconstant line having a width smaller than that of the distributedconstant line constituting the second conductor part 12. The width ofthe distributed constant line of the third conductor part 13 may be thesame as or different from the width of the distributed constant lineconstituting the first conductor part 11.

A configuration of the second resonator 20 is basically the same as theconfiguration of the first resonator 10. Specifically, the secondresonator 20 includes a first conductor part 21 and a second conductorpart 22 having an impedance smaller than that of the first conductorpart 21. The first conductor part 21 and the second conductor part 22are electrically connected to each other. The first conductor part 21 isconnected to ground. Each of the first conductor part 21 and the secondconductor part 22 is a distributed constant line. In particular, in thepresent embodiment, the first conductor part 21 is a distributedconstant line having a small width, and the second conductor part 22 isa distributed constant line having a width larger than that of the firstconductor part 21.

The second resonator 20 further includes a third conductor part 23electrically connecting the first conductor part 21 and the secondconductor part 22. The third conductor part 23 may include a distributedconstant line having a width smaller than that of the distributedconstant line constituting the second conductor part 22. The width ofthe distributed constant line of the third conductor part 23 may be thesame as or different from the width of the distributed constant lineconstituting the first conductor part 21.

The third resonator 30 includes a first conductor part 31 and a secondconductor part 32 having an impedance smaller than that of the firstconductor part 31. The first conductor part 31 and the second conductorpart 32 are electrically connected to each other. The first conductorpart 31 is connected to ground. Each of the first conductor part 31 andthe second conductor part 32 is a distributed constant line. Inparticular, in the present embodiment, the first conductor part 31 is adistributed constant line having a small width, and the second conductorpart 32 is a distributed constant line having a width larger than thatof the first conductor part 31.

All the first to third resonators 10, 20, and 30 are each astepped-impedance resonator composed of a distributed constant linehaving a small width and a distributed constant line having a largewidth. All the first to third resonators 10, 20, and 30 are each aquarter-wavelength resonator with one end being short-circuited and theother end being open.

The impedance of each of the first conductor parts 11, 21, and 31 iswithin a range from 15 Ω to 35 Ω, for example. The impedance of each ofthe second conductor parts 12, 22, and 32 is within a range from 1 Ω to5 Ω, for example. Here, the ratio of the impedance of the secondconductor part to the impedance of the first conductor part in each ofthe first to third resonators 10, 20, and 30 is referred to as animpedance ratio. In each of the first to third resonators 10, 20, and30, the impedance ratio is smaller than 1. For example, by adjusting thewidths of the distributed constant line configuring the first conductorpart and the distributed constant line configuring the second conductorpart, the impedance ratio can be adjusted. For a smaller impedanceratio, the width of the distributed constant line configuring the firstconductor part is relatively small, and the width of the distributedconstant line configuring the second conductor part is relatively large.

The filter device 1 further includes a first port 2, a second port 3,and conductor portions 4 and 5. The first to third resonators 10, 20,and 30 are arranged between the first port 2 and the second port 3 inthe circuit configuration.

The conductor portion 4 electrically connects the first port 2 and thefirst resonator 10. The conductor portion 4 is connected, at one endthereof, to the first port 2. The conductor portion 4 is connected, atthe other end thereof, to the first resonator 10 between the firstconductor part 11 and the third conductor part 13.

The conductor portion 5 electrically connects the second port 3 and thesecond resonator 20. The conductor portion 5 is connected, at one endthereof, to the second port 3. The conductor portion 5 is connected, atthe other end thereof, to the second resonator 20 between the firstconductor part 21 and the third conductor part 23.

Next, other configurations of the filter device 1 will be described withreference to FIG. 2 . FIG. 2 is a perspective view showing an outsideview of the filter device 1.

The filter device 1 further includes a stack 50. The stack 50 includes aplurality of dielectric layers stacked together and a plurality ofconductor layers and a plurality of through holes formed in theplurality of dielectric layers. The first to third resonators 10, 20,and 30 are integrated with the stack 50. The first to third resonators10, 20, and 30 are formed by using the plurality of conductor layers.

The stack 50 has a first surface 50A and a second surface 50B located atboth ends in a stacking direction T of the plurality of dielectriclayers, and four side surfaces 50C to 50F connecting the first surface50A and the second surface 50B. The side surfaces 50C and 50D areopposite to each other. The side surfaces 50E and 50F are opposite toeach other. The side surfaces 50C to 50F are perpendicular to the firstsurface 50A and the second surface 50B.

Here, X, Y, and Z directions are defined as shown in FIG. 2 . The X, Y,and Z directions are orthogonal to one another. In the presentembodiment, a direction parallel to the stacking direction T will bereferred to as the Z direction. The opposite directions to the X, Y, andZ directions are defined as -X, -Y, and -Z directions, respectively.

As shown in FIG. 2 , the first surface 50A is located at the end of thestack 50 in the -Z direction. The first surface 50A is also the bottomsurface of the stack 50. The second surface 50B is located at the end ofthe stack 50 in the Z direction. The second surface 50B is also the topsurface of the stack 50. The side surface 50C is located at the end ofthe stack 50 in the -X direction. The side surface 50D is located at theend of the stack 50 in the X direction. The side surface 50E is locatedat the end of the stack 50 in the -Y direction. The side surface 50F islocated at the end of the stack 50 in the Y direction.

The plane shape of the stack 50 when seen in the Z direction, i.e., theshape of the first surface 50A or the second surface 50B, is long in onedirection. In particular, in the present embodiment, the plane shape ofthe stack 50 when seen in the Z direction is a rectangular shape that islong in a direction parallel to the X direction.

The filter device 1 further includes a plurality of terminals 111, 112,113, 114, 115, and 116 provided on the first surface 50A of the stack50. The terminal 111 extends in the Y direction near the side surface50C. The terminal 112 extends in the Y direction near the side surface50D. The terminals 113 to 116 are arranged between the terminal 111 andthe terminal 112. The terminals 113 and 114 are arranged in this ordernear the side surface 50E in the X direction. The terminals 115 and 116are arranged in this order near the side surface 50F in the X direction.

The terminal 111 corresponds to the first port 2, and the terminal 112corresponds to the second port 3. Thus, the first and second ports 2 and3 are provided on the first surface 50A of the stack 50. The terminals113 to 116 are connected to ground. Hereinafter, the terminal 111 isalso referred to as a first terminal 111, the terminal 112 is alsoreferred to as a second terminal 112, and the terminals 113 to 116 arealso referred to as ground terminals 113 to 116.

Next, an example of the plurality of dielectric layers and the pluralityof conductor layers constituting the stack 50 will be described withreference to FIG. 3A to FIG. 5C. In this example, the stack 50 includesnine dielectric layers stacked together. The nine dielectric layers willbe referred to as a first to a ninth dielectric layer in the order frombottom to top. The first to ninth dielectric layers are denoted byreference numerals 51 to 59, respectively.

FIG. 3A shows the patterned surface of the first dielectric layer 51.The terminals 111, 112, 113, 114, 115, and 116 are formed on thepatterned surface of the dielectric layer 51. Through holes 51T1, 51T2,51T3, 51T4, 51T5, and 51T6 connected respectively to the terminals 111,112, 113, 114, 115, and 116 are formed in the dielectric layer 51.

FIG. 3B shows the patterned surface of the second dielectric layer 52. Aconductor layer 521 is formed on the patterned surface of the dielectriclayer 52. Further, through holes 52T1, 52T2, 52T3, 52T4, 52T5, and 52T6are formed in the dielectric layer 52. The through holes 51T1 and 51T2formed in the dielectric layer 51 are connected to the through holes52T1 and 52T2, respectively. The through holes 51T3 to 51T6 formed inthe dielectric layer 51 and the through holes 52T3 to 52T6 are connectedto the conductor layer 521.

FIG. 3C shows the patterned surface of the third dielectric layer 53.Conductor layers 531, 532, 533, and 534 are formed on the patternedsurface of the dielectric layer 53. The conductor layer 532 is connectedto the conductor layer 531. The conductor layer 534 is connected to theconductor layer 533. In FIG. 3C, each of the boundary between theconductor layer 531 and the conductor layer 532 and the boundary betweenthe conductor layer 533 and the conductor layer 534 is indicated by adotted line.

Through holes 53T1, 53T2, 53T3, 53T4, 53T5, and 53T6 are formed in thedielectric layer 53. The through hole 52T1 formed in the dielectriclayer 52 and the through hole 53T1 are connected to the conductor layer532. The through hole 52T2 formed in the dielectric layer 52 and thethrough hole 53T2 are connected to the conductor layer 534. The throughholes 52T3 to 52T6 formed in the dielectric layer 52 are connected tothe through holes 53T3 to 53T6, respectively.

FIG. 4A shows the patterned surface of the fourth dielectric layer 54. Aconductor layer 541 is formed on the patterned surface of the dielectriclayer 54. Through holes 54T1, 54T2, 54T3, 54T4, 54T5, 54T6, and 54T7 areformed in the dielectric layer 54. The through holes 53T1 to 53T6 formedin the dielectric layer 53 are connected to the through holes 54T1 to54T6, respectively. The through hole 54T7 is connected to the conductorlayer 541.

FIG. 4B shows the patterned surface of the fifth dielectric layer 55. Aconductor layer 551 is formed on the patterned surface of the dielectriclayer 55. Through holes 55T1, 55T2, 55T7, and 55T8 are formed in thedielectric layer 55. The through holes 54T1, 54T2, and 54T7 formed inthe dielectric layer 54 are connected to the through holes 55T1, 55T2,and 55T7, respectively. The through holes 54T3 to 54T6 formed in thedielectric layer 54 and the through hole 55T8 are connected to theconductor layer 551.

FIG. 4C shows the patterned surface of the sixth dielectric layer 56.Through holes 56T1, 56T2, 56T7, and 56T8 are formed in the dielectriclayer 56. The through holes 55T1, 55T2, 55T7, and 55T8 formed in thedielectric layer 55 are connected to the through holes 56T1, 56T2, 56T7,and 56T8, respectively.

FIG. 5A shows the patterned surface of the seventh dielectric layer 57.Conductor layers 571 and 572 are formed on the patterned surface of thedielectric layer 57. Each of the conductor layers 571 and 572 has afirst end and a second end opposite to each other. The first end of theconductor layer 571 and the first end of the conductor layer 572 areconnected to each other. In FIG. 5A, the boundary between the conductorlayer 571 and the conductor layer 572 is indicated by a dotted line. Thethrough hole 56T1 formed in the dielectric layer 56 is connected to aportion near the second end of the conductor layer 571. The through hole56T2 formed in the dielectric layer 56 is connected to a portion nearthe second end of the conductor layer 572.

Through holes 57T7 and 57T8 are formed in the dielectric layer 57. Thethrough hole 56T7 formed in the dielectric layer 56 is connected to thethrough hole 57T7. The through hole 56T8 formed in the dielectric layer56 and the through hole 57T8 are connected to a portion near the firstend of the conductor layer 571 and a portion near the first end of theconductor layer 572.

FIG. 5B shows the patterned surface of the eighth dielectric layer 58. Aconductor layer 581 is formed on the patterned surface of the dielectriclayer 58. The conductor layer 581 has a first end and a second endopposite to each other. The through hole 57T7 formed in the dielectriclayer 57 is connected to a portion near the first end of the conductorlayer 581.

A through hole 58T8 is formed in the dielectric layer 58. The throughhole 57T8 formed in the dielectric layer 57 and the through hole 58T8are connected to a portion near the second end of the conductor layer581.

FIG. 5C shows the patterned surface of the ninth dielectric layer 59. Aconductor layer 591 is formed on the patterned surface of the dielectriclayer 59. The through hole 58T8 formed in the dielectric layer 58 isconnected to the conductor layer 591.

The stack 50 shown in FIG. 2 is formed by stacking the first to ninthdielectric layers 51 to 59 such that the patterned surface of the firstdielectric layer 51 serves as the first surface 50A of the stack 50 andthe surface of the ninth dielectric layer 59 opposite to the patternedsurface thereof serves as the second surface 50B of the stack 50.

FIG. 6 shows the inside of the stack 50 formed by stacking the first toninth dielectric layers 51 to 59. As shown in FIG. 6 , the plurality ofconductor layers and the plurality of through holes shown in FIGS. 3A to5C are stacked inside the stack 50.

Correspondences between the circuit components of the filter device 1shown in FIG. 1 and the internal components of the stack 50 shown inFIG. 3A to FIG. 5C will now be described. First, the first resonator 10will be described. The first conductor part 11 is formed of theconductor layer 571. The second conductor part 12 is formed of theconductor layer 531. The third conductor part 13 is formed of theconductor layer 532.

The conductor layer 532 (third conductor part 13) and the through holes53T1, 54T1, 55T1, and 56T1 connect the conductor layer 571 forming thefirst conductor part 11 and the conductor layer 531 forming the secondconductor part 12. The conductor layer 571 forming the first conductorpart 11 is connected to the ground terminals 113 to 116 via the throughholes 51T3 to 51T6, the conductor layer 521, the through holes 52T3 to52T6 and 53T3 to 53T6, the through holes 54T3 to 54T6, the conductorlayer 551, and the through holes 55T8 and 56T8.

Next, the second resonator 20 will be described. The first conductorpart 21 is formed of the conductor layer 572. The second conductor part22 is formed of the conductor layer 533. The third conductor part 23 isformed of the conductor layer 534.

The conductor layer 534 (third conductor part 23) and the through holes53T2, 54T2, 55T2, and 56T2 connect the conductor layer 572 forming thefirst conductor part 21 and the conductor layer 533 forming the secondconductor part 22. The conductor layer 572 forming the first conductorpart 21 is connected to the ground terminals 113 to 116 via the throughholes 51T3 to 51T6, the conductor layer 521, the through holes 52T3 to52T6 and 53T3 to 53T6, the through holes 54T3 to 54T6, the conductorlayer 551, and the through holes 55T8 and 56T8.

Next, the third resonator 30 will be described. The first conductor part31 is formed of the conductor layer 581. The second conductor part 32 isformed of the conductor layer 541.

The conductor layer 581 forming the first conductor part 31 is connectedto the ground terminals 113 to 116 via the through holes 51T3 to 51T6,the conductor layer 521, the through holes 52T3 to 52T6 and 53T3 to53T6, the through holes 54T3 to 54T6, the conductor layer 551, and thethrough holes 55T8, 56T8, and 57T8.

Next, the conductor portions 4 and 5 will be described. The conductorportion 4 is formed of the through holes 51T1 and 52T1. The through hole51T1 is connected to the first terminal 111. The through hole 52T1 isconnected to the conductor layer 532 forming the third conductor part 13and is also connected to the conductor layer 571 forming the firstconductor part 11 via the through holes 53T1, 54T1, 55T1, and 56T1.

The conductor portion 5 is formed of the through holes 51T2 and 52T2.The through hole 51T2 is connected to the second terminal 112. Thethrough hole 52T2 is connected to the conductor layer 534 forming thethird conductor part 23 and is also connected to the conductor layer 572forming the first conductor part 21 via the through holes 53T2, 54T2,55T2, and 56T2.

Next, the structural features of the filter device 1 according to thepresent embodiment will be described with reference to FIG. 2 to FIG. 8. FIG. 7 and FIG. 8 are each a perspective view showing part of aninside of the stack 50. FIG. 7 mainly shows a plurality of conductorlayers and a plurality of through holes constituting the first andsecond resonators 10 and 20. FIG. 8 mainly shows a plurality ofconductor layers and a plurality of through holes constituting the thirdresonator 30.

The first resonator 10 is arranged in an area on the -X direction sidein the stack 50. In other words, the first resonator 10 is arranged at aposition closer to the side surface 50C than the side surface 50D. Asshown in FIG. 7 , the first conductor part 11 (conductor layer 571) andthe second conductor part 12 (conductor layer 531) of the firstresonator 10 are arranged at positions different from each other in thestacking direction T. The second conductor part 12 is arranged betweenthe first surface 50A, where the plurality of terminals 111 to 116 arearranged, and the first conductor part 11.

The first conductor part 11 (conductor layer 571) includes a pluralityof portions extending in a plurality of directions that are orthogonalto the stacking direction T. In particular, in the present embodiment,the first conductor part 11 (conductor layer 571) includes four portionseach extending in a direction parallel to the X direction and threeportions each extending in a direction parallel to the Y direction.

The shape of the second conductor part 12 (conductor layer 531) is longin a direction crossing the longitudinal direction of the stack 50. Inparticular, in the present embodiment, the shape of the second conductorpart 12 (conductor layer 531) is a rectangular shape that is long in adirection parallel to the Y direction.

The second resonator 20 is arranged in an area on the X direction sidein the stack 50. In other words, the second resonator 20 is arranged ata position closer to the side surface 50D than the side surface 50C. Asshown in FIG. 7 , the first conductor part 21 (conductor layer 572) andthe second conductor part 22 (conductor layer 533) of the secondresonator 20 are arranged at positions different from each other in thestacking direction T. The second conductor part 22 is arranged betweenthe first surface 50A, where the plurality of terminals 111 to 116 arearranged, and the first conductor part 21.

The first conductor part 21 (conductor layer 572) includes a pluralityof portions extending in a plurality of directions that are orthogonalto the stacking direction T. In particular, in the present embodiment,the first conductor part 21 (conductor layer 572) includes four portionseach extending in a direction parallel to the X direction and threeportions each extending in a direction parallel to the Y direction.

The shape of the second conductor part 22 (conductor layer 533) is longin a direction crossing the longitudinal direction of the stack 50. Inparticular, in the present embodiment, the shape of the second conductorpart 22 (conductor layer 533) is a rectangular shape that is long in adirection parallel to the Y direction.

At least part of the third resonator 30 is arranged between the firstresonator 10 and the second resonator 20 when seen in the Z direction.In particular, in the present embodiment, part of the third resonator 30is arranged between the first resonator 10 and the second resonator 20.

As shown in FIG. 8 , the first conductor part 31 (conductor layer 581)and the second conductor part 32 (conductor layer 541) of the thirdresonator 30 are arranged at positions different from each other in thestacking direction T. The second conductor part 32 is arranged betweenthe first surface 50A, where the plurality of terminals 111 to 116 arearranged, and the first conductor part 31.

The first conductor part 31 (conductor layer 581) includes a pluralityof portions extending in a plurality of directions that are orthogonalto the stacking direction T. In particular, in the present embodiment,the first conductor part 31 (conductor layer 581) includes threeportions each extending in a direction parallel to the X direction andfour portions each extending in a direction parallel to the Y direction.

The first conductor part 31 (conductor layer 581) has an asymmetricalshape with respect to a given XZ plane crossing the first conductor part31 and also has an asymmetrical shape with respect to a given YZ planecrossing the first conductor part 31. Hereinafter, the given XZ planecrossing the first conductor part 31 is referred to as a first virtualplane, and the given YZ plane crossing the first conductor part 31 isreferred to as a second virtual plane. The first virtual plane may crossthe center of the stack 50 in a direction parallel to the Y direction.The second virtual plane may cross the center of the stack 50 in adirection parallel to the X direction.

The shape of the second conductor part 32 (conductor layer 541) is longin the longitudinal direction of the stack 50. In particular, in thepresent embodiment, the shape of the second conductor part 32 (conductorlayer 541) is a rectangular shape that is long in a direction parallelto the X direction.

As shown in FIG. 5A and FIG. 6 , the first conductor part 11 (conductorlayer 571) of the first resonator 10 and the first conductor part 21(conductor layer 572) of the second resonator 20 are arranged at thesame position in the stacking direction T. As shown in FIG. 5A, FIG. 5B,and FIG. 6 , the first conductor part 31 (conductor layer 581) of thethird resonator 30 is arranged at a position different from thepositions of the first conductor parts 11 and 21 in the stackingdirection T. Part of the first conductor part 11 and part of the firstconductor part 21 overlap the first conductor part 31 when seen in the Zdirection. The shape of the first conductor part 31 is different fromthe shape of the first conductor part 11 and the shape of the firstconductor part 21.

As shown in FIG. 3C and FIG. 6 , the second conductor part 12 (conductorlayer 531) of the first resonator 10 and the second conductor part 22(conductor layer 533) of the second resonator 20 are arranged at thesame position in the stacking direction T. As shown in FIG. 3C, FIG. 4A,and FIG. 6 , the second conductor part 32 (conductor layer 541) of thethird resonator 30 is arranged at a position different from thepositions of the second conductor parts 12 and 22 in the stackingdirection T. Part of the second conductor part 12 and part of the secondconductor part 22 overlap the second conductor part 32 when seen in theZ direction. The shape of the second conductor part 32 is different fromthe shape of the second conductor part 12 and the shape of the secondconductor part 22.

As described above, in the present embodiment, the first conductor part11 and the second conductor part 12 of the first resonator 10 arearranged at positions different from each other in the stackingdirection T. Thus, according to the present embodiment, the firstconductor part 11 and the second conductor part 12 can be arranged whileoverlapping each other. Hence, according to the present embodiment, thearea for arranging the first resonator 10 can be made substantiallysmaller than that for a case where the first conductor part 11 and thesecond conductor part 12 are formed in the same dielectric layer to bearranged in the same position in the stacking direction T.

The description of the first resonator 10 above is also applicable tothe second and third resonators 20 and 30. In view of these, accordingto the present embodiment, the filter device 1 can be miniaturized.

In the present embodiment, part of the first conductor part 11 of thefirst resonator 10 and part of the first conductor part 21 of the secondresonator 20 overlap the first conductor part 31 of the third resonator30 when seen in the Z direction, and part of the second conductor part12 of the first resonator 10 and part of the second conductor part 22 ofthe second resonator 20 overlap the second conductor part 32 of thethird resonator 30 when seen in the Z direction. Also in view of this,according to the present embodiment, the filter device 1 can beminiaturized.

In the present embodiment, each of the first conductor parts 11, 21, and31 includes the plurality of portions extending in the plurality ofdirections different from each other. Hence, according to the presentembodiment, the area for arranging each of the first conductor parts 11,21, and 31 can be made substantially smaller than that for a case whereeach of the first conductor parts 11, 21, and 31 extends in onedirection.

In the present embodiment, the first conductor part 31 has anasymmetrical shape as that described above. Thus, according to thepresent embodiment, the interaction to occur between the first conductorpart 11 and the first conductor part 31 and the interaction to occurbetween the first conductor part 21 and the first conductor part 31 canbe made different from each other. This can, for example, reducespurious to be generated in a higher frequency region than the passband.

In the present embodiment, the conductor layer 591 is connected to theground terminals 113 to 116 via the through holes 51T3 to 51T6, theconductor layer 521, the through holes 52T3 to 52T6 and 53T3 to 53T6,the through holes 54T3 to 54T6, the conductor layer 551, and the throughholes 55T8, 56T8, 57T8, and 58T8. The first to third resonators 10, 20,and 30 are arranged between the conductor layer 521 and the conductorlayer 591. Each of the conductor layers 521 and 591 overlap the first tothird resonators 10, 20, and 30 when seen in the Z direction. Theconductor layers 521 and 591 function as shields.

Next, an example of characteristics of the filter device 1 according tothe present embodiment will be described. FIG. 9 is a characteristicchart showing an example of pass attenuation characteristics of thefilter device 1. In FIG. 9 , the horizontal axis represents frequency,and the vertical axis represents attenuation. As shown in FIG. 9 , thefilter device 1 according to the present embodiment functions as aband-pass filter. FIG. 9 shows an example in which the filter device 1is designed to have a passband of 2.3 GHz to 3.3 GHz.

Second Embodiment

A description of the configuration of a multilayered filter device ofthe second embodiment of the present invention will be given withreference to FIGS. 10 to 12 . FIG. 10 is a circuit diagram showing acircuit configuration of the multilayered filter device according to thepresent embodiment. FIG. 11 is an explanatory diagram showing apatterned surface of a seventh dielectric layer of the presentembodiment. FIG. 12 is a perspective view showing an inside of a stackof the multilayered filter device according to the present embodiment.

A filter device 1 according to the present embodiment differs from thatof the first embodiment in the following respects. The filter device 1according to the present embodiment includes a first stub resonator 91electrically connected to the first conductor part 11 of the firstresonator 10, and a second stub resonator 92 electrically connected tothe first conductor part 21 of the second resonator 20. Each of thefirst and second stub resonators 91 and 92 is a distributed constantline.

The first stub resonator 91 is connected in the middle of the firstconductor part 11. In FIG. 10 , for the first conductor part 11, aportion located between a connecting point with the first stub resonator91 and the second conductor part 12 in the circuit configuration isindicated by a reference numeral 11A, and a portion located between aconnecting point with the first stub resonator 91 and the ground in thecircuit configuration is indicated by a reference numeral 11B.

The second stub resonator 92 is connected in the middle of the firstconductor part 21. In FIG. 10 , for the first conductor part 21, aportion located between a connecting point with the second stubresonator 92 and the second conductor part 22 in the circuitconfiguration is indicated by a reference numeral 21A, and a portionlocated between a connecting point with the second stub resonator 92 andthe ground in the circuit configuration is indicated by a referencenumeral 21B.

In the present embodiment, the stack 50 includes a dielectric layer 157shown in FIG. 11 instead of the seventh dielectric layer 57 in the firstembodiment. Similarly to the dielectric layer 57, conductor layers 571and 572 are formed on a patterned surface of the dielectric layer 157.Conductor layers 573 and 574 are further formed on the patterned surfaceof the dielectric layer 157. The conductor layer 573 is connected in themiddle of the conductor layer 571. The conductor layer 574 is connectedin the middle of the conductor layer 572. In FIG. 11 , each of theboundary between the conductor layer 571 and the conductor layer 573 andthe boundary between the conductor layer 572 and the conductor layer 574is indicated by a dotted line.

The first stub resonator 91 is formed of the conductor layer 572. Thesecond stub resonator 92 is constituted of the conductor layer 574. Theshape of the conductor layer 572 and the shape of the conductor layer574 may be the same or different from each other. In the example shownin FIG. 11 , the shape of the conductor layer 572 and the shape of theconductor layer 574 are different from each other.

The first and second stub resonators 91 and 92 are used, for example, tocontrol spurious to be generated in a higher frequency region than apassband. Each of the first and second stub resonators 91 and 92 may bean open stub with one end being open or may be a short stub with one endbeing connected to ground.

The configuration, operation, and effects of the present embodiment areotherwise the same as those of the first embodiment.

Third Embodiment

A description of the configuration of a multilayered filter device ofthe third embodiment of the present invention will be given withreference to FIG. 13 . FIG. 13 is a circuit diagram showing a circuitconfiguration of the multilayered filter device according to the presentembodiment.

A filter device 1 according to the present embodiment differs from thatof the second embodiment in the following respects. The filter device 1according to the present embodiment includes a fourth resonator 40. Thefourth resonator 40 is arranged between the second resonator 20 and thethird resonator 30 in the circuit configuration. In the presentembodiment, the first to fourth resonators 10, 20, 30, and 40 areconfigured so that the first resonator 10 and the third resonator 30 areadjacent to each other in the circuit configuration to beelectromagnetically coupled to each other, the third resonator 30 andthe fourth resonator 40 are adjacent to each other in the circuitconfiguration to be electromagnetically coupled to each other, and thesecond resonator 20 and the fourth resonator 40 are adjacent to eachother in the circuit configuration to be electromagnetically coupled toeach other. In FIG. 13 , a curve with a sign K13 represents an electricfield coupling between the first resonator 10 and the third resonator30, a curve with a sign K34 represents a magnetic field coupling betweenthe third resonator 30 and the fourth resonator 40, and a curve with asign K24 represents an electric field coupling between the secondresonator 20 and the fourth resonator 40.

A configuration of the fourth resonator 40 is basically the same as theconfiguration of the third resonator 30. Specifically, the fourthresonator 40 includes a first conductor part 41 and a second conductorpart 42 having an impedance smaller than that of the first conductorpart 41. The first conductor part 41 and the second conductor part 42are electrically connected to each other. The first conductor part 41 isconnected to ground. Each of the first conductor part 41 and the secondconductor part 42 is a distributed constant line. In particular, in thepresent embodiment, the first conductor part 41 is a distributedconstant line having a small width, and the second conductor part 42 isa distributed constant line having a width larger than that of the firstconductor part 41.

The fourth resonator 40, similarly to the first to third resonators 10,20, and 30, is a stepped-impedance resonator composed of a distributedconstant line having a small width and a distributed constant linehaving a large width.

Although not shown, the first conductor part 41 and the second conductorpart 42 of the fourth resonator 40, similarly to the first conductorpart 31 and the second conductor part 32 of the third resonator 30, arearranged at positions different from each other in the stackingdirection T. The first conductor part 31 and the first conductor part 41may be arranged at the same position in the stacking direction T or maybe arranged at positions different from each other in the stackingdirection T. Similarly, the second conductor part 32 and the secondconductor part 42 may be arranged at the same position in the stackingdirection T or may be arranged at positions different from each other inthe stacking direction T.

In the present embodiment, at least part of the third resonator 30 andat least part of the fourth resonator 40 are arranged between the firstresonator 10 and the second resonator 20 when seen in the Z direction(refer to FIG. 2 ).

In the present embodiment, part of the first conductor part 11 of thefirst resonator 10 may overlap the first conductor part 31 of the thirdresonator 30 when seen in the Z direction. In this case, part of thefirst conductor part 21 of the second resonator 20 may overlap the firstconductor part 41 of the fourth resonator 40 when seen in the Zdirection.

In the present embodiment, part of the second conductor part 12 of thefirst resonator 10 may overlap the second conductor part 32 of the thirdresonator 30 when seen in the Z direction. In this case, part of thesecond conductor part 22 of the second resonator 20 may overlap thesecond conductor part 42 of the fourth resonator 40 when seen in the Zdirection.

The filter device 1 according to the present embodiment further includesa third stub resonator 93 electrically connected to the first conductorpart 31 of the third resonator 30, and a fourth stub resonator 94electrically connected to the first conductor part 41 of the fourthresonator 40. Each of the third and fourth stub resonators 93 and 94 isa distributed constant line.

The third stub resonator 93 is connected in the middle of the firstconductor part 31. In FIG. 13 , for the first conductor part 31, aportion located between a connecting point with the third stub resonator93 and the second conductor part 32 in the circuit configuration isindicated by a reference numeral 31A, and a portion located between aconnecting point with the third stub resonator 93 and the ground in thecircuit configuration is indicated by a reference numeral 31B.

The fourth stub resonator 94 is connected in the middle of the firstconductor part 41. In FIG. 13 , for the first conductor part 41, aportion located between a connecting point with the fourth stubresonator 94 and the second conductor part 42 in the circuitconfiguration is indicated by a reference numeral 41A, and a portionlocated between a connecting point with the fourth stub resonator 94 andthe ground in the circuit configuration is indicated by a referencenumeral 41B.

The third and fourth stub resonators 93 and 94 are used, for example, tocontrol spurious to be generated in a higher frequency region than apassband. Each of the third and fourth stub resonators 93 and 94 may bean open stub with one end being open or may be a short stub with one endbeing connected to ground.

The configuration, operation, and effects of the present embodiment areotherwise the same as those of the second embodiment.

The present invention is not limited to the foregoing embodiments, andvarious modifications may be made thereto. For example, the number andconfiguration of resonators are not limited to those shown in theembodiments, and any number and configuration of resonators may beemployed as long as the scope of the claims is satisfied. The number ofresonators may be one, two, or five or more.

Obviously, many modifications and variations of the present inventionare possible in the light of the above teachings. Thus, it is to beunderstood that, within the scope of the appended claims and equivalentsthereof, the invention may be practiced in other embodiments than theforegoing most preferable embodiments.

What is claimed is:
 1. A multilayered filter device comprising: a stackincluding a plurality of dielectric layers stacked together; and atleast one resonator integrated with the stack, wherein the at least oneresonator includes a first conductor part and a second conductor partelectrically connected to the first conductor part and having animpedance smaller than an impedance of the first conductor part, and thefirst conductor part and the second conductor part are arranged atpositions different from each other in a stacking direction of theplurality of dielectric layers.
 2. The multilayered filter deviceaccording to claim 1, wherein each of the first conductor part and thesecond conductor part is a distributed constant line.
 3. Themultilayered filter device according to claim 1, further comprising atleast one through hole connecting the first conductor part and thesecond conductor part.
 4. The multilayered filter device according toclaim 1, further comprising a plurality of terminals, wherein the stackincludes a first surface and a second surface located at both ends inthe stacking direction, the plurality of terminals are arranged on thefirst surface, and the second conductor part is arranged between thefirst conductor part and the first surface in the stacking direction. 5.The multilayered filter device according to claim 1, wherein the firstconductor part includes a plurality of portions extending in a pluralityof directions that are orthogonal to the stacking direction and aredifferent from each other.
 6. The multilayered filter device accordingto claim 1, wherein a plane shape of the stack when seen in onedirection parallel to the stacking direction is long in one direction,and a shape of the second conductor part is long in a longitudinaldirection of the plane shape of the stack.
 7. The multilayered filterdevice according to claim 1, wherein a plane shape of the stack whenseen in one direction parallel to the stacking direction is long in onedirection, and a shape of the second conductor part is long in adirection crossing a longitudinal direction of the plane shape of thestack.
 8. The multilayered filter device according to claim 1, whereinthe at least one resonator includes a first resonator, a secondresonator, and a third resonator arranged between the first resonatorand the second resonator in a circuit configuration.
 9. The multilayeredfilter device according to claim 8, wherein the stack includes a firstside surface and a second side surface located at both ends in adirection orthogonal to the stacking direction, the first resonator isarranged at a position closer to the first side surface than the secondside surface, and the second resonator is arranged at a position closerto the second side surface than the first side surface.
 10. Themultilayered filter device according to claim 8, wherein at least partof the third resonator is arranged between the first resonator and thesecond resonator when seen in one direction parallel to the stackingdirection.
 11. The multilayered filter device according to claim 8,wherein the first conductor part of the first resonator and the firstconductor part of the second resonator are arranged at a same positionin the stacking direction, and the first conductor part of the thirdresonator is arranged at a position different from a position of thefirst conductor part of each of the first resonator and the secondresonator in the stacking direction.
 12. The multilayered filter deviceaccording to claim 11, wherein part of the first conductor part of thefirst resonator and part of the first conductor part of the secondresonator overlap the first conductor part of the third resonator whenseen in one direction parallel to the stacking direction.
 13. Themultilayered filter device according to claim 8, wherein the secondconductor part of the first resonator and the second conductor part ofthe second resonator are arranged at a same position in the stackingdirection, and the second conductor part of the third resonator isarranged at a position different from a position of the second conductorpart of each of the first resonator and the second resonator in thestacking direction.
 14. The multilayered filter device according toclaim 13, wherein part of the second conductor part of the firstresonator and part of the second conductor part of the second resonatoroverlap the second conductor part of the third resonator when seen inone direction parallel to the stacking direction.
 15. The multilayeredfilter device according to claim 8, wherein the first conductor part ofthe third resonator has an asymmetrical shape.
 16. The multilayeredfilter device according to claim 8, wherein a shape of the firstconductor part of the third resonator is different from a shape of thefirst conductor part of the first resonator and a shape of the firstconductor part of the second resonator, and a shape of the secondconductor part of the third resonator is different from a shape of thesecond conductor part of the first resonator and a shape of the secondconductor part of the second resonator.
 17. The multilayered filterdevice according to claim 8, further comprising: a first stub resonatorelectrically connected to the first conductor part of the firstresonator; and a second stub resonator electrically connected to thefirst conductor part of the second resonator.